Good reminder that you want the diagnosis tools in place and working before you get an actual problem in production.

A sound list of advises, applicable to most database systems of course.

OK, that looks like cool challenges to train your troubleshooting skills.

Obviously didn't read it all but this is a very large knowledge repository of practices from many companies one can get inspired by to work on Site Reliability Engineering. It is especially comprehensive since it's not only about technical tips but also deals with hiring, team building and culture (which is almost as important if not more).